hddn loads the redaction workspace into your browser.
After that, your browser can open and edit your PDF locally. Your file does not need to be sent anywhere for processing.
For a deeper explanation, read the Trust Center.
FAQ
PDF Redaction FAQ
Answers about local PDF redaction, privacy, uploads, file limits, and what to expect before you export a redacted PDF.
How does this work without uploading my file?
Is my file safe?
Your PDF stays on your device.
We do not upload, store, or send your PDF anywhere for processing. You can verify this by using offline mode after the tools are loaded.
Can I use it with airplane mode on?
Yes. Load offline tools first, then disconnect and refresh the redaction workspace.
Text-based PDFs can be redacted offline after the workspace is loaded. For scanned PDFs, load the needed OCR tools before disconnecting.
What is saved for offline use?
Tool files only: the app shell, PDF engine, OCR tools, fonts, and detection dictionaries.
Offline mode does not save your PDF, extracted text, previews, markings, redaction choices, or exported files.
Why should I trust a new app?
You do not have to rely only on trust.
hddn can run offline after loading the tools, so you can disconnect, refresh, and test redaction while your device is offline.
For a deeper explanation, read the Trust Center.
Does hddn use AI?
hddn does not use any remote AI service or external API. Any detection used by the app runs locally in your browser on your device.
Can you see my documents?
No.
We have no access to your files because they never leave your device.
What data do you collect?
We only use Google Analytics, if you accept it, to understand general site usage.
We do not collect or analyze your documents.
Do you use cookies?
Yes, one cookie.
It stores whether you accepted or declined analytics. It does not track your activity or store personal data.
Is it really free?
Yes.
hddn is free to use. No signup, document upload account, or payment step.
What file types are supported?
PDF files only.
Are there any limits?
Up to 25 MB per file.
Up to 30 pages per document.
Does it work on mobile?
Yes, it works in modern browsers on phones, tablets, and computers.
Is redaction permanent?
Yes.
When you export the file, the selected data is permanently removed from the PDF.
What if something is missed?
You can always add your own redactions.
You should review the document before exporting to make sure everything that should be hidden is removed.
Why do I need to review before exporting?
The tool suggests what might be sensitive, but you decide what to remove.
This helps you stay in control of your document.
Why is there no upload?
Because the redaction workspace runs in your browser.
Load offline tools, disconnect, refresh /redact, and you can test that the core workflow still runs without a document-processing server.